The present invention relates to non-combustion chemical heat sources, such as electrochemical heat sources, materials used to make chemical heat sources, and methods of forming chemical heat sources. Specifically, the present invention relates to a heat source used in a smoking article to heat tobacco, thereby producing a tobacco flavor or tobacco-flavored aerosol.
The heat sources of the present invention are particularly adapted for use in smoking articles that are capable of providing the user with the pleasures of smoking (e.g., smoking taste, feel, satisfaction, and the like), without burning tobacco or any other material, without producing sidestream smoke or odor, and without producing combustion products such as carbon monoxide. As used herein, the term “smoking article” includes cigarettes, cigars, pipes, and the like, which use tobacco in various forms.
Smoking articles have had various shapes, and have been composed of various types of components. Examples of smoking articles or cigarettes with electrochemical heat sources are described in U.S. Pat. No. 4,938,236 to Banerjee et al.; U.S. Pat. No. 4,955,399 to Potter et al.; U.S. Pat. No. 5,285,798 to Banerjee et al.; U.S. Pat. No. 5,357,984 to Farrier et al.; U.S. Pat. No. 5,538,020 to Farrier et al.; and U.S. Pat. No. 5,593,792 to Farrier et al., which are all incorporated herein by reference. Banerjee et al. ('798) describes one embodiment of a cigarette with a heat source that included a heat chamber, a metallic electrochemical agent, and an activating solution separated from the electrochemical agent by a frangible seal. The electrochemical agent was pushed through the seal into the activating solution to begin the electrochemical reaction to generate modest amounts of heat. The use of this heat source was limited because it created an uncontrolled reaction and could sustain temperatures of about 100° C. in temperature.
Although much work has been done in this field, it would be desirable to produce an improved heat source that can attain, maintain, and sustain, higher than 100° C. temperatures and can be used to construct a smoking article that can provide many of the pleasures of cigarette or pipe smoking, but does not burn tobacco or other material, and which does not produce any combustion products.
It would also be desirable to develop an improved non-combustion, chemical heat source that can be used for other uses. For example, U.S. Pat. No. 3,623,471 to Bogue discloses a short circuited battery of a flexible shape that acts as a heater and suggests that it may be used to heat a can of soup, c-rations, and building materials. U.S. Pat. Nos. 3,774,589 and 3,851,654 to Kober disclose an electrochemical heat source and suggest that the heat produced thereby can be used for heating hair for waving, a hot compress, and heating food.
Additional patents disclosing electrochemical or exothermic chemical reactions and some of the uses described thereof include: U.S. Pat. No. 3,766,079 (heating a resin used to seal joints in pipeline); U.S. Pat. No. 3,871,357 (heating precooked food); U.S. Pat. No. 3,878,118 (heating cosmetic compositions); U.S. Pat. No. 3,884,216 (heating diver's suit); U.S. Pat. No. 3,906,926 (curing underwater adhesives); U.S. Pat. Nos. 3,920,476; 3,942,511; 3,993,577 and 4,017,414 (heating diver's suit, machinery and equipment); U.S. Pat. No. 4,080,953 (heating blanket); U.S. Pat. No. 4,094,298 (heating prepackaged food); U.S. Pat. No. 4,095,583 (hand warming pads); U.S. Pat. No. 4,098,258 (heating beef stew and other precooked foods); U.S. Pat. No. 4,142,508 (heating electrical insulator to shrink it over a wire splice); U.S. Pat. No. 4,186,746 (body warmer); U.S. Pat. Nos. 4,223,661 and 4,264,362 (heating diver's suit and melting ice); U.S. Pat. No. 4,338,098 (heating frozen foods and controlled release agricultural chemicals).